<h1>Incompatible changes made in the past</h1>

<h2> Between 1.24 and 1.25</h2>

<ul>
	Changed the handling of coordinate
	system. Instead of passing a string such as "linear", "log", 
	or "category" to "x_coord_system" (or "y_coord_system") attribute of
	the area.T object, we now pass an instance of linear_coord.T,
	log_coord.T, or category_coord.T to "x_coord" or "y_coord" attribute.
	This allows for	cleaner separation between the coordinate
	system and the drawing of "area" components. For example:

<pre>
	ar = area.T(x_coord_system = "linear", ...)
</pre>

	becomes

<pre>
	ar = area.T(x_coord = linear_coord.T(), ...)
</pre>

(In fact, because x_coord defaults to linear_coord.T(), you can just write
ar = area.T(...) in the above example).

<pre>
	ar = area.T(x_coord_system = "category", x_category_data = data,
	            x_category_col = col, ...)
</pre>
	becomes
	
<pre>
	ar = area.T(x_coord = category_coord.T(data, col), ...)
</pre>
</ul>

<h2> Between 1.20 and 1.21</h2>

<ul>
<li> pychart/line_style.py (init): grayXXdashY is renamed to
	grayXX_dashY. For example, gray7dash3 is now gray70_dash3.
<li> pychart/color.py (T.__str__): Changed the naming scheme of
	color.grayXX to match that of rgb.txt in X. For example, gray1 is
	renamed to gray10, gray5 is renamed to gray50, etc. Also, to avoid
	confusion, colors known as "gray1" in rgb.txt (or gray2, gray3,
	etc) are renamed to gray01, gray02, gray03, etc.
</ul>